Axelar message passing

Adapt the basic oracle for zero-to-prototype to work with axelar
1. Configure Prover to talk to oracle (or update protocol so SP selects #12)
2. Figure out gas service and how to pay for it (probably users need to submit payment along with their data?)
3. Make sure we're using latest things to avoid crazy high fees (figure out what squid router is etc)

Start by reading the basic oracle prototype and issue #12 to understand how the Prover should communicate with the oracle or how the SP should select it. Investigate Axelar's gas service and the role of Squid Router, including how users would provide payment with their data. Done means the prototype passes messages through Axelar with current fee practices and a defined payment flow.

Written by the indexing model from the issue text.